#61
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however, do they really have to be mica?
81-RDE5C3A331J2M1H3A 75-561R10TCCQ82 my set has all ceramic capacitors. Perhaps someone with a ctc-5 can give some insight,
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=^-^= Yasashii yoru ni hitori utau uta. Asu wa kimi to utaou. Yume no tsubasa ni notte. いとおしい人のために |
#62
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Quote:
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#63
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Looks like C115 is in a rectangular package, I assumed its mica VS round ceramic.
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#64
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that blue one is a modern Multilayer ceramic capacitor, like made for SMT, with leads on it for through hole.
__________________
=^-^= Yasashii yoru ni hitori utau uta. Asu wa kimi to utaou. Yume no tsubasa ni notte. いとおしい人のために |
#65
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Wax Capacitors in CTC-5 Set
There were some RCA black and white sets 20 inch and above, in the 1950s, that had over 50 wax caps. RCA loved them waxies. Part of that is the belief that tubular capacitors automatically have more consistent high frequency response. Admittedly it is much harder to properly select ceramics for high frequencies.
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Audiokarma |
#66
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I should give an update! After completing my yearly recurrent training I was able to dedicate time to troubleshooting the horizontal section. Symptoms were horizontal off frequency, low HV.... and it caused TWO 6CG7's to short out internally.
I took three micamold style caps out of circuit and tested them. C115 was the culprit, leaking at only 50 volts. It's supposed to be a 1000-volt cap. I also replaced a couple out of tolerance resistors, nothing too crazy. Two 82K caps were both showing 91k. I'm back to having a running CTC-5 although I'm dreading a full convergence alignment. The sides are really bad. -- Matt Davala |
#67
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The convergence of my CTC5 wasn't bad once I read and followed the CTC5 service manual. The convergence process is somewhat different from later sets.
I have been able to achieve good overall convergence but it takes patience. Also be aware of the general complaint of low high voltage. To get a bit higher voltage and improve regulation, I replaced the HV rectifier with a solid state 3A3. |
#68
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I'd describe it as follows:
The CTC-5 does not have diodes to clamp the dynamic waveforms at the center like later sets, so in the CTC-5, points halfway between the center and edge stay motionless while the center moves the opposite of the edges. The trick is to rough in the DC in the center, then adjust the dynamics to get parallel R, G, and B lines, then fine tune the DC for best overall (and then maybe retweak the dynamic a tiny bit). Hope your DC control pots are in good condition and not burned just at the proper setting point like mine were (both originals and replacements from a parts donor). 100 ohm carbon pot with tap at 25 ohms IIRC. Really pushing the limit on low total resistance for a carbon pot. I made up a substitution with 6 wirewound pots and three switches to pick a tap just above or just below or at the nominal tap point. If I was doing it again, I'd be tempted to try subbing a later cloverleaf with permanent magnet DC adjustments, but I don't know if the coils would be right for the dynamics. |
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